States that change from secondary to primary seat belt enforcement laws have increased rates of seat belt use after primary enforcement laws go into effect (Dihn-Zarr 2001). Changing from secondary to primary enforcement has been shown to increase seat belt use during the day and night (NHTSA-Chaudhary 2010). Primary enforcement laws appear to have the largest effects among high-risk drivers, such as alcohol-impaired drivers, and among populations with lower rates of seat belt use, such as blacks and Hispanics (Dihn-Zarr 2001).

Despite concern, there is no evidence that minorities are stopped at higher rates than whites for seat belt violations in states with primary enforcement laws. Several states have added anti-harassment language to their primary seat belt laws to reduce the risk of such differential enforcement (Dihn-Zarr 2001).

Primary law enforcement can include paid media efforts (NHTSA-Nichols 2010, NHTSA-Hedlund 2008). Primary seat belt laws that are enforced with well-publicized seat belt use checkpoints appear to yield more benefits through quality adjusted life years (QALYs) saved and injuries prevented than they cost to implement (Miller TR, Levy DT. Cost-outcome analysis in injury prevention and control: Eighty-four recent estimates for the United States. Medical Care. 2000;38(6):562-82.Link to original source (journal subscription may be required for access)Miller 2000).

Impact on Disparities

Likely to decrease disparities

Implementation Examples

As of May 2015, 34 states and Washington, DC have primary seat belt laws for front seat occupants; in 17 of these states and Washington, DC, primary enforcement laws also cover rear seats (GHSA-Seat belt laws).

Citations - Implementation Examples

Date Last Updated

Scientifically Supported: Strategies with this rating are most likely to make a difference. These strategies have been tested in many robust studies with consistently positive results.

Some Evidence: Strategies with this rating are likely to work, but further research is needed to confirm effects. These strategies have been tested more than once and results trend positive overall.

Expert Opinion: Strategies with this rating are recommended by credible, impartial experts but have limited research documenting effects; further research, often with stronger designs, is needed to confirm effects.

Insufficient Evidence: Strategies with this rating have limited research documenting effects. These strategies need further research, often with stronger designs, to confirm effects.

Mixed Evidence: Strategies with this rating have been tested more than once and results are inconsistent or trend negative; further research is needed to confirm effects.

Evidence of Ineffectiveness: Strategies with this rating are not good investments. These strategies have been tested in many robust studies with consistently negative and sometimes harmful results.